The present invention relates to a copying machine capable performing a stepless changing of its copying magnification and, more particularly, it relates to a magnification control device capable of setting the magnification in the form of linear and area magnifications.
When the magnification is changed to meet the size of the copying paper, plural fixed magnification keys are provided to set the magnification to meet the change in the size of the copying paper which is done, for example from size A3 to size A4, from size A4 to size B4, and from size B4 to A3. However, the copying machines which use a stepless process to change their magnification are on the market these days and their magnification setting is attained by inputting an optional numeral value by means of numeral ten keys or the like. When reduction is done from size A3 to size A4, for example, the numeral value which represents the length ratio of the sides between sizes A3 and A4 is inputted to set the magnification. Since the length ratio is .sqroot.2:1, the numeral value which is to be inputted by the ten keys is 0.707, which is called linear magnification.
On the other hand, the area ratio between sizes A3 and A4 is 2:1, which is equal to 0.5 and this 0.5 is called area magnification. When reduction from size A3 to size A4 is denoted by the linear magnification, it is 0.707 and when it is represented by the area magnification, it is 0.5. Conventionally, the linear magnification was employed by all copying machines.
When the operator operates the stepless magnification copying machine, he must input a numeral value by means of the ten keys, usually keeping the linear magnification in his mind. It is, however, difficult for the ordinary operators to conceptually convert enlargement and reduction of copying paper in the form of linear magnification. When they want to reduce the size of the copying paper to a size a little smaller in area ratio than 1/2, for example, they cannot easily or quickly obtain the desired area ratio by inputting its numeral value which is represented by the linear magnification.